The present invention relates to a bonded composite of a first thin-section element of sheet material and a second thin-section element bonded together by bond elements defining a bond pattern. More particularly, one of the contemplated applications for the present invention is in bonding outer cover and body-side liner thin-section elements of absorbent articles to one another.
Personal care absorbent articles have been known for a long time as hygiene products. They find use, for example, as diapers, incontinence inlays, or in women""s sanitary pads. Such personal care absorbent articles are constructed in such a way that they can absorb and store liquid bodily excretions such as urine, menstrual fluid, or blood. Women""s sanitary pads are used, for example, to absorb the liquids excreted prior to, during and, after menstruation.
In absorbent articles, the portions of the article where different layers or components are bonded to each other tend to incur significant stress concentrations, and in absorbent articles using conventional bond patterns, tend to fracture at those bonded locations under such stresses. In conventional patterns used in absorbent articles, bond locations are disposed in uniform and crossing straight lines and straight rows of circular bond elements. The inventors herein have noted that such bond configuration has been found to enhance the probability that the absorbent article will tear and that the tear propagates along the side edge of the bond pattern. Tearing properties of such conventional patterns can be compared to perforated paper forms.
The problem addressed in the present invention is thus to provide a bonded composite demonstrating a bond pattern, and an absorbent article implementing the bond pattern, whereby the configuration of the bond pattern discourages the possibility for fracture of the bonded composite or absorbent article at the bond pattern.
The present invention solves this problem by means of the bonded composite as well as the absorbent article both disclosed and described in the independent claims. Additional advantageous embodiments of the absorbent article in accord with the invention and of the process in accordance with the invention arise from the dependent claims, the specification, and the drawings.
It is an object of this invention to reduce the ease of tearing of a bonded composite or absorbent article by introducing bonding locations and configurations which discourage straight fracture of the bonded materials, and encourage dissipating an initially concentrated force within a substantial area of the bonding pattern.
It is still another object to provide a bond pattern wherein bond elements on the interior of the bond pattern are closer together than bond elements proximate the side edges of the bond pattern.
In a first family of embodiments, the invention comprehends a bonded composite, and personal care absorbent articles made therewith. The bonded composite comprises, as a first thin-section element, a first layer of thin-section sheet material, and a second thin-section material element bonded to the first thin-section element by bond elements defining a bond pattern. The bond pattern has a pattern length as well as a pattern width represented by first and second side edges of the bond pattern. A central longitudinal axis divides the bond pattern longitudinally. The side edges of the bond pattern, and the overall area of the bond pattern, are defined generally by those areas of the respective thin-section elements which participate in absorbing and dissipating, by operation of the bond pattern, stresses received into the bond pattern. The bond pattern reflects application of force urging the first and second thin-section elements toward each other in face-to-face relationship to form an array of separate, distinct, and spaced elongate bond elements affixing the first and second thin-section elements to each other. The bond elements typically include stress receptor elements, stress transfer and dissipation elements, and optionally stress termination elements. The stress receptor elements are employed as a first sub-array of longitudinally-oriented separate, distinct, and spaced elements disposed proximate the side edges of, and along the length of, the bond pattern. The stress transfer and dissipation elements are employed as a second sub-array of longitudinally-oriented separate, distinct, and spaced elements spaced along the length of the bond pattern, inwardly of the side edges of the bond pattern and generally inwardly of the stress receptor elements. Respective transfer and dissipation elements have first ends disposed at an interior portion of the bond pattern, and extending to second ends adjacent the side edges of the bond pattern between respective ones of the stress receptor elements. The stress transfer and dissipation elements direct stresses inwardly into the interior portion of the bond pattern, such stresses being dissipated in the interior portion of the bond pattern.
The bonded composite can comprise, as ones of the bond elements, a third sub-array of longitudinally-oriented separate, distinct, and spaced stress termination elements disposed generally inwardly of the transfer and dissipation elements, on opposing sides of, and oriented generally along, the central longitudinal axis. The stress termination elements tend to accumulate and coordinate termination of stresses transferred into an interior portion of the bond pattern.
The transfer and dissipation elements can have first ends disposed relatively inwardly from the side edges and second ends disposed toward the side edges such that the second ends tend to receive stress imposed from outside the bond pattern and the first ends tend to dissipate the stress at interior portions of the bond pattern.
In some embodiments, the bond pattern comprises first and second opposing pattern combinations corresponding to first and second sides of the bond pattern, on opposing sides of the longitudinal axis. Each such pattern combination comprises ones of the stress receptor elements at the side edges of the bond pattern, ones of the transfer and dissipation elements being disposed inwardly of the stress receptor elements, and ones of the stress termination elements being disposed inwardly of the transfer and dissipation elements.
In preferred embodiments, the first and second pattern combinations are substantially the same.
In some embodiments, the first and second bond patterns are positioned along the length of the pattern such that the pattern combinations are asymmetric with respect to each other. Although asymmetric with each other, the respective first and second pattern combinations are preferably each internally symmetric as well as being symmetric with respect to the length of the bond pattern.
Bonds corresponding to the bond elements can be activated by application of thermal energy or ultrasonic-frequency energy to at least one of the thin-section elements. Preferably, at least one of the first thin-section element and the second thin-section element comprises polymeric material selected from the group consisting of polyolefins including polyethylenes and polypropylenes, polyesters, and polyamides, and copolymers, mixtures, and blends of such polymeric materials.
In some embodiments, at least one of the first thin-section element and the second thin-section element comprises a fibrous web defining a multiplicity of randomly-spaced small openings extending from a major surface of the web into the interior of the web.
In some embodiments, the stress receptor elements and the stress transfer and dissipation elements, in combination, alternate along the length, and on opposing side edges, of the bond pattern, and thereby provide side-to-side balance to the bond element area of the bond pattern, so as to tend to attenuate torsional forces on the bonding apparatus used in forming the respective bond elements.
In preferred embodiments, the stress receptor elements and the stress transfer and dissipation elements, in combination, alternate along the length, and on opposing side edges, of the bond pattern, and thereby provide continuous, side-to-side balance to the bond element area of the bond pattern, so as to tend to attenuate torsional forces on the bonding apparatus used in forming the respective bond elements.
The bond elements preferably occupy from about 10 percent to about 40 percent, more preferably from about 12 percent to about 30 percent, and still more preferably from about 15 percent to about 25 percent of the overall bond area of the bond pattern.
In the absorbent article implementation, the first and second thin-section elements can, in combination, comprise an outer cover and a body side liner. At least one of the body side liner and the outer cover can comprise polymeric material selected from the group consisting of polyolefins including polyethylenes and polypropylenes, polyesters, and polyamides, and mixtures, copolymers, and blends of such polymeric materials. The body side liner can comprise material selected from the group consisting of porous foams, reticulated foams, apertured polymeric films, polymeric fibers, and natural fibers.
Further to the personal care absorbent article implementation, the length of the bond pattern can extend from the front portion of the absorbent article to the rear portion of the absorbent article.
In some embodiments, the crotch portion is devoid of the bond pattern.
In personal care absorbent article implementations, the width of the bond pattern is preferably about 4 millimeters to about 14 millimeters, more preferably about 5 millimeters to about 12 millimeters.
Such personal care absorbent article can comprise, for example and without limitation, a feminine hygiene article, a diaper, or an adult incontinence product.
In a second family of embodiments, the invention comprehends a bonded composite, and personal care absorbent articles made therewith. The bonded composite comprises, as a first thin-section element, a first layer of thin-section sheet material, and a second thin-section element bonded to the first thin-section element by bond elements defining a bond pattern. The bond pattern has a pattern length, a pattern width represented by first and second side edges of the bond pattern, and a central longitudinal axis extending along an interior portion of the bond pattern. The side edges of the bond pattern are defined generally by those areas of the respective thin-section elements which participate in absorbing and dissipating, by operation of the bond pattern, stresses received into the bond pattern. The bond pattern reflects application of force urging the first and second thin-section elements toward each other in face-to-face relationship to form an array of separate, distinct, and spaced elongate bond elements affixing the first and second thin-section elements to each other. Ones of the bond elements in the interior portion of the bond pattern are spaced closer together than the bond elements proximate the side edges.
Correspondingly, the bond elements disposed toward the side edges are spaced farther apart than the bond elements in the interior portion of the bond pattern.
In some embodiments, the bond pattern comprises, as ones of the bond elements, a first sub-array of longitudinally-oriented separate, distinct, and spaced stress receptor elements disposed at the side edges of, and along the length of, the bond pattern, and as ones of the bond elements, a second sub-array of longitudinally-oriented separate, distinct, and spaced transfer and dissipation elements spaced along the length of the bond pattern, inwardly of the side edges of the bond pattern and generally inwardly of the stress receptor elements. Respective transfer and dissipation elements have first ends disposed at interior portions of the bond pattern, and extend to second ends adjacent the side edges of the bond pattern between respective ones of the stress receptor elements. The stress transfer and dissipation elements direct stresses inwardly into the interior portion of the bond pattern. Such stresses are generally dissipated in the interior portion of the bond pattern.
In preferred embodiments, stress receptor elements are disposed at the side edges of the bond pattern, and spaced at first common distances from each other along the length of the bond pattern. Transfer and dissipation elements are disposed inwardly of the side edges and inwardly of the stress receptor elements, and at second distances from the stress receptor elements less than the spacing of the stress receptor elements from each other.